Hi Nick,
The PIXMA MG6150 does not appear to be a printer supporting the driverless AirPrint technology.
You could of course try to (reset the printing system, re-add the printer, and) use the latest available Canon driver for macOS Sierra 10.12, but (unless this is a 64-bit driver) it will probably not work.
If nothing else works, you may have to look for alternative solutions. However, be careful, and download files from trustworthy sources only.
Safely open apps on your Mac - Apple Support
Apparently, there is an experimental Gutenprint driver for your printer model. However, this would really be experimental, and you must know exactly what you are doing.
If absolutely necessary, you may even want to try running Windows in a virtual machine on your Mac, and test whether printing would be possible from there.
Reset the Mac printing system to solve a problem - Apple Support
Add a printer on Mac - Apple Support